High temperature creep-fatigue-oxidation interactions in 9-12%Cr martensitic steels

摘要

Detailed observations of fractured specimens of 9-12%Cr martensitic steels subjected to creep-fatigue loadings at 823 K were carried out. Observations revealed that oxidation phenomena strongly influence the creep-fatigue lifetime whereas no creep damage (cavities) can be observed in the present loading conditions. Two main interaction mechanisms between creep, fatigue and oxidation damage were high_lighted. These two damage mechanisms correspond to two distinct domains of loading (expressed in terms of total strain range and holding period duration). Based on the identified mechanisms a creep-fatigue lifetime prediction model is proposed. The crack initiation is approached by the Tanaka and Mura model, whereas the crack propagation phase is accounted by the Tomkins formulation.